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The Tangled History of Connecticut's Anchisaurus

East Coast dinosaurs are relatively rare finds, often because the geological formations in which they rest have been built over. Dinosaurs surely remain to be found under parking lots, housing developments and city streets, and one of the now-lost dinosaur quarries is located in Manchester, Connec...

East Coast dinosaurs are relatively rare finds, often because the geological formations in which they rest
have been built over. Dinosaurs surely remain to be found under parking lots, housing developments and city streets, and one of the now-lost dinosaur quarries is located in Manchester, Connecticut.

During the 19th century the remains of several sauropodomorph dinosaurs were found in the Nutmeg State. These were the long-necked, small-headed precursors of the later, gigantic
sauropod dinosaurs. Most of these were finds were very fragmentary, but in the late 1880s three partial skeletons were found at Wolcott's Quarry in Manchester. (This site has since been filled in.) Because this locality was not far from Yale, the famous paleontologist
O.C. Marsh got the duty of describing the specimens.

Paleontologist Adam Yates, in his recent reanalysis of these dinosaurs, recounted the taxonomic tangle Marsh created. Despite the fact that all three specimens came from the same Early Jurassic-age quarry, Marsh attributed each fragmentary skeleton to a different species. Marsh named the first specimen
Anchisaurus major (1889), the second was named
Anchisaurus colurus (1891), and the third was given the title
Anchisaurus solus (1892), although these names were not stable. Marsh renamed the first specimen
Ammosaurus in 1891, the second specimen was renamed
Yaleosaurus by
Friedrich von Huene in 1932, and von Huene also transferred the third specimen to another species of
Ammosaurus. What a mess!

Debates over the right name for these dinosaurs continued for decades and even reached into the early 21st century. Paleontologists eventually agreed that all the specimens belonged to just one species, but should that species be
Ammosaurus or
Anchisaurus? Yates makes a convincing argument that
Anchisaurus polyzelus is the dinosaur's proper name.

About two decades prior to the Wolcott Quarry finds, the partial skeleton of a sauropodomorph dinosaur was found in Springfield, Massachusetts. It was given the name
Megadactylus polzelus, but was changed to
Amphisaurus by Marsh in 1882 and finally
Anchisaurus in 1885 since both of the previously-used names were occupied. Obviously
Anchisaurus and the Wolcott Quarry skeletons were the same general type of dinosaur, but a lack of distinguishing characteristics in the overlapping portions of the skeletons prevented paleontologists from grouping them all under the same name.

After looking at the skeletons again, however, Yates found peculiar features of the hip blade and part of the fused vertebrae which make up the hip. These features unite all the New England specimens, and this means that the older name—
Anchisaurus—gets preference over Marsh's "
Ammosaurus" for the Wolcott skeletons. After nearly a century and a half of uncertainty, we can now say that
Anchisaurus polyzelus is the proper name for these dinosaurs.

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